1. Field of the Invention
The invention relates to the field of rehabilitation methods and apparatus for retraining of patients with motor impairment such as stroke, spinal cord injury, traumatic brain injury, cerebral palsy, multiple sclerosis, peripheral nerve injury or the like.
2. Description of the Prior Art
Each year in the U.S. over 700,000 people survive a stroke. Approximately 50% of stroke survivors have chronic hemiparesis. Movement impairments are typically treated with intensive, hands-on physical and occupational therapy for several weeks after the initial injury. Unfortunately, due to economic pressures on the U.S. health care system, stroke patients are receiving less therapy than before. Consequently, the home rehabilitation that results from these pressures is self directed with little professional or quantitative feedback. Approximately 26% of chronic stroke survivors become dependent in activities of daily living. A growing body of evidence suggests that both acute and chronic stroke survivors can improve movement ability with intensive, supervised training.
When people suffer a severe stroke or other serious neural injury, they often have difficulty lifting the arm against gravity, and opening and closing the hand. Their inability to move the upper limb in a useful way is very frustrating, and they stop trying to move the limb, leading eventually to a further decreased ability to use the limb because of the physiological changes in muscle and neural tissue associated with prolonged disuse. Rehabilitation therapists and other caregivers encourage their patients to practice moving in order to regain some function, but one-on-one, hands-on interaction with a professional caregiver is expensive. People often do not continue to practice moving once they leave the hospital environment.
Several researchers are addressing this goal by developing robotic devices that can assist in arm and hand movement therapy following stroke. Initial studies with MIT-MANUS (see U.S. Pat. No. 5,466,213), MIME, the ARM Guide, Gentle-S and Rutgers Master II-ND have been promising. Acute and chronic stroke subjects who receive more therapy with a robotic device can recover more movement ability. Matched amounts of robotic and conventional therapy produced comparable therapeutic benefits for chronic stroke subjects.
Despite these promising initial results, it still remains unclear as to whether the robotic features of these devices (i.e. the ability to apply programmable forces to the patient's limb), are important to improving movement recovery. That is, technology that allows patients to practice movement therapy without robotic actuation may also be effective in improving recovery. While non-robotic devices are less useful for studying a broad range of interactive therapy techniques, they might ultimately be more practical because they avoid the expense and safety concerns associated with robotic actuators.
There is a long history of using non-robotic technology in rehabilitation clinics to partially automate physical rehabilitation following stroke. Mobile arm supports, overhead slings, elastic bands, and weights allow patients to practice therapy semi-independently from therapists. However, these devices typically suffer from three key limitations: they can be difficult to adjust for different levels of impairment; their relevance to functional activities is indirect; and they provide little feedback to the patient or therapist about movement recovery.
What is needed is an apparatus and method that allows the rapidly growing stroke population to practice intensive movement training without the expense of a continuously present therapist.